Indented lists not supported

[JohnRoux]

Hey,

I'm not super familiar with Pandoc otherwise this would be a PR, but I'm wanting to have bullet and ordered list indentation work correctly.
Currenltly this lua extension will just make all lists on the same level and not respect the indentation.

Alternatively is there any good documentation for how to make a pandoc extension? I've found suprisingly little infomration about the function paramater options